1. Field of the Invention
The present invention relates to a computer implemented method, program, and system for generating RDF expressions from predetermined data.
2. Description of Related Art
In recent years, RDF (Resource Description Framework) format has been used as a mechanism for describing resources on the web, as disclosed in Japanese Patent Application Publication 2005-242934 and Japanese Patent Application Publication 2006-302085. Furthermore, Bizer, Tom Heath, Tim Berners-Lee, Lined Data—The Story So Far, International Journal on Semantic Web and Information Systems, 5 (3), 2009, describes Linked Data where RDF format data is used in coordination on a web mechanism as a mechanism for global information disclosure. Also see, Open Services for Lifecycle Collaboration (OSLC), http://open-services.net/, for a description on using Linked Data for information coordination within an enterprise.
Tools that provide Linked Data include tools that store and provide RDF data, and tools that convert non-RDF data managed by existing tools to RDF and then provide RDF data.
Furthermore, tools that use Linked Data include tools that obtain data by traversing links based on a user request, and tools that crawl over tools that provide Linked Data beforehand and create an index in order to make data access more efficient.
FIG. 1 is a diagram illustrating an example of a configuration where a plurality of computers is connected by a network in order to use this type of tool. In other words, computers 104, 106, 108, 110, 112, 114, 116, and 118 are connected to a network 102 which is typically a LAN or WAN. Computer 104 and computer 110 store a tool that stores and provides RDF data.
Computer 106 and computer 112 store an existing tool. Herein, data that is handled by an existing tool refers to records that are stored in a relational database, application language objects that are accessed by the API of an existing tool, and structured data in XML, HTML, CSV.
Computer 108 and computer 114 store a tool that manages the existing tools on computer 106 and computer 112, and converts data that is not RDF to RDF and then provides, or in other words, stores a tool that converts and provides Linked Data.
Computer 116 stores a tool that obtains data by traversing links based on a user request. Computer 118 stores a tool that crawls over tools that provide Linked Data beforehand and creates an index.
With this configuration, each time computer 116 and computer 118 accesses the tool that converts and provides Linked Data on computer 108 and computer 114, the existing tool on computer 106 or computer 112 is accessed in order to return a response.
In particular, when the tool that crawls over tools that provide Linked Data beforehand and creates an index on computer 118 crawls over the tool that converts and provides Linked Data on computer 108 and computer 114, a plurality of accesses are concentrated in order to generate a response for the request. Therefore, access to the existing tool in order to respond to the requests from the crawler becomes a bottleneck, and there is a problem that the throughput of the entire system is reduced.
Soeren Auer, Sebastian Dietzold, Jens Lehmann, Sebastian Hellmann, David Aumueller, Universitaet Leipzig, Postfach Leipzig, Triplify—Light-Weight Linked Data Publication from Relational Databases, WWW 2009, describes technology that converts data of an existing database to RDF in accordance with a mapping designation. Using the technology described therein, a plurality of triples is simultaneously generated from the results of a single existing database query, thus preventing an increase in the number of accesses. However, access to the existing database always occurs when accessing the conversion tool, so the throughput of the entire system is not improved.